Allotropy or
allotropism is the property of some chemical elements to exist in two or more different forms, known as
allotropes of these elements. Allotropes are different structural modifications of an element
; the atoms of the element are bonded together in a different manner. For example, the allotropes of carbon include diamond (where the carbon atoms are bonded together in a tetrahedral lattice arrangement), graphite (where the carbon atoms are bonded together in sheets of a hexagonal lattice).